High speed belt printer with internal hammer



Jan. 5, 1965 w. ca. PAIGE 3,164,084

HIGH SPEED BELT PRINTER WITH INTERNAL HAMMER Filed Jan. 18, 1962 2 s-Sheet 1 50 Jan. 5, 1965 w. e. PAIGE 3,164,084

HIGH SPEED BELT PRINTER WITH INTERNAL HAMMER Filed Jan. 18, 1962 2 Sheets-Sheet 2 I NVEN TOR. M41750 z/rm/ Q/f Irma/1? to. use in processes for updating printed records,

Briefly, the present invention, in a basic form, includes 1 a drum platen and a plurality of rollers for. tightly platen.

United States Patent 3,164,084 HIGH SPEED BELT PRKTTTER WITH INTERNAL HAMMER Walter Grifin Paige, Pasadena, Calii, assignorto Burroughs Corporation, Detroit, Mich, a corporation of Michigan Filed Tan. 18, 1962, Ser. No. 167,019 Claims. (Cl. 191-93) This invention is directed to improvements in high speed printers and more particularly to a novel high speed platen printer.

In general, high speed printers include a moving type surface having type characters ismpressed thereon in a column array and a print hammer associated with each type column. Apparatusis also included for feeding a print medium, such as paper, between the type surface and the hammers. To print, the hammers are selectively propelled against the paper to force the paper into contact with the type surface.

Since the type surface and hammers lie on opposite sides of the paper, the feed apparatus is necessarily located outside the print area. Thus, to impart guiding movement to the paper, the feed apparatus must either drive the edges of the paper or grasp the top and bottom of the paper and pull the paper past the print hammers.

' have been directed to the handling of paper of a single size. Accordingly, the use of high speed printers in printing on documents of varying sizes has been very limited.

Further, the feed apparatus employedfin such high speed printers does not lend itself to selective positioning or repositioning of documents. Thus, in the past, high speed printers have found only a limited use in printing processes for updating fprinted records such as those ap pearing on ledge-rs, checks, or tabularcards. Also, since, in printing with the .prior art type of printer, the hammers strike thepaper to force the paper against the type surface, when it is desired to print a number of carbon copies the hammers are required to v compress the many sheets of paper against the type surface. Dueto air between the sheets of paper, a complete compressing of the paper against the type surface is not possible and as a result reliable printing through to the carbon Icopies isnot possible.

In contrast to the conventional high speed printer, the present invention provides a relatively inexpensive, comthe type characters, as well as the hammers and hammer actuating mechanisms on one side of the print material, a plurality of print mediums may be tightl compressed against a platen. Thus the type characters, in striking the print mediums, produce clear carbon copies of the type characters.

By turning the platen in a manner similar to that of the platen of a typewriter, documents of varying sizes may be brought into proximity with the type characters for selective printing thereon. Also, by selectively controlling the rotation of the platen, the high speed printer of the present invention may be utilized in the reprinting and updatin of records on documents of varying sizes.

The above, as well as other features of the present invention, may be more clearly understood by reference to the following detailed description when considered with the drawings, in which:

FIGURE 1 is a schematic representation of a sectional side view of one form of the high speed platen printer of the present invention;

FIGURE 2 is an expanded schematic representation of a section of the flexible belt utilized in the printer of the present invention; and

FIGURE 3 is a schematic representation of a sectional front view of the printer.

Referring to the drawings, the high speed printer of V the present invention includes a platen 10. By way of example only, the platen It? is represented as a drum platen having a facing of rubber-like material indicated atv 12 Asindicatedby the arrow 14, the platen 16 is rotatable about its longitudinal axisrepresented at 16 in a-manner similar to the platen on a typewriter.

Associated with the platen it) are pressure rollers 18, i 2d and 22. The pressure rollers'llti and 29 are coupled together and press upward toward the centerof the palten 25 are located adjacent the rollers 20 and 22, respectively.

is guided by the guides 24 and.'25 between the platen 10 pact, yet rugged, high speed printer which is capable of I rapid, clear and simultaneous printing on one or more.

and the pressure roller'22 to maintain pressure contact of the paper with the surface of the platen 10.

By Way of example only, to feed paper tangentially to theplaten lthguide members represented at 26 and 27 I are provided. which extend adjacent the platen 19. By

print mediums of varying size and which is ideally suited pressing one or more sheets of a printmedium against the type charactersragainst the print material.

Due to the positioning of theflexible belts, including- Mounted represented at 28 and-3d, areprovided. The guide mem- The toothed belts t direction away from the platen 10.

means not specifically shown, paper is guided along the guidemember 2.16 and forced downward by the guide-- member 2? in a direction tangential to the'platen It) to i apoint between the pressure roller 18 and the platen 1t Toguide the paper from the palten ltl, guide members,

bers 28 and 30 extend tangentially to the platen 10 a'dja v cent the pressure roller 22. Thus, as .the paper passes between the roller 22 and the :platen 10, it extends between, a

the guide members 28yand 3i) and is passed in an upward- The platen 10 maybe moved by anyone of a number of well known 'apparatus. for example, the platen Ill may be controlled by 'a'moton drive which moves the platen in steps similar to that of; typewriter platen and may stopthe platen at'any point-,to provide alignment of the paper with theprint mechanism o'f'the present invention for adding information to documents of varying sizes.v

An example 'of -afd 'rive mechanism which may be a driyengshai'ts .52 jPlZtf-ll 10. v V 1 v, r H Q jlnthis manner the belts 42 are, aligned next to each other on the pulley arrangements 4 landl6 and are driven} by'a rotation of the drive shaft 52 past the platen lllsuch that the'type characters, pass in succession immediately employed with the platen of the present invention is described indetail in the patent'to E I. Rabenda, No. 2,569,829, issued October 2, 1951.

-'A pair of ribbon spools 32 and 34 are located on either side of the platen lit. As illustrated, a ribbon 36 wound around the spool 32 passes over a ribbon shield 33 and over an opening 49 to the spool 34. By way of example, the guides 24 and Z-dmay form apart of the ribbon shield 33. The opening 4% is immediately adjacent the platen 10 and between the roller 2% and 22. Thus, to print on paper extending around the platen it), a type character may be propelled against the ribbon 36 passing over the opening do to press the ribbon into contact with the paper.

To provide' such print operation the present invention 1 includes a plurality of flexible, continuous, inwardly toothed belts 42, which aredriven past the platen lo adjacent the opening 4s. Each belt 42 includes a plurality of type characters, disposed on its outer surface. Each type character is aligned opposite a tooth. The teeth as Well as the type characters are spaced one from another such thatin moving pastthe platen lit the type charac= ters are exposed one at a time to the platen through the opening 4%; V

' To drive the belts 42, the belts are positioned over a pair of-grooved pulley arrangements 44 and 46. The pulley arrangement 44 includes a plurality of individual grooved pulleys 48 separated by spacer members s. The pulleys 43 are 'lreyed to a drive, shaft 52 as represented at in-FIGURE 1 The pulleys 4-8 arernaintained on 'the drive shaft 51- by a pair'of retaining members as and 58 which fit arojurid the drive shaft S2 at either end of the pulleys, 48 (see arouses The grooves of the pulleys-a8 mate withthe teeth of the belts 42.

" The pulley-arrangement 45 also includes aplurality oi individually'toothedlpulleys 6d separated by spacer ""62. The pulleys till-are mounted for free rotation about t a driven shaft 63 and are maintained onthe shaft 63' by 'apair of retaining members 64 and as which extend around the driven shaft as at either end of'the pulleys-60 (see FlGURE 3).."The grooves of the pulleys 60 mate,

-As speeificallyrepresented in .FlGURE 3, thedriv'e" shaft 52 ,is journalled to a frame arrangement dli by a pair of bearing configurations 7t and 72.

v ln-this manner thedrive shaft 52 is cantilevered from 'the frameed substantia'lly normal thereto. Due to the bearing configurw. V

ti'ons'ltl and '72, the drive shaft 52 is free to rotate (in response to a motor 'dr ive'meansi notspecificalIyShOWn) about its longitudinal axis 74 which extends substantially parallel to the axis 16 of the'jplaten it]. As represented platen Ill.

The driven shatt63 is also jour nalled to the frame ar range'ment, 63 by apai'r of bearing configurations 7,6 and 78. In. this 'inanner,-1-tl1e' driven shaftbd :is also cantidinal axis dllwhich extends substantially pmallelto the axis 156 of theplaten 16. As represent'ed, the drive and and 63 lie. on opposite sides of the .adjacenttheopeningdtl.

Positionedlinter'nal to .the pulley ar'rangements 4M- andfld is a "support member 82'.

As illustrated in FIGURE the support member $2 belts 42 andvv between the a ratus Q8 for tensioning the belts d2 as they pass over the pulleys 44 and 46. The sections of the support member 82 may be denoted as the hammer support member 34, the actuator support member 56, and a pair of coupling members 88 and 9%.

As represented in PEGURE 1, the actuator support member 86 extends between the pulley arrangements 44 and 45 along an inner surface of the belts 412 remote from the platen 1d. The actuator support member 86 includes an inwardly recessed portion 1% facing the inner surface of the belts 42 remote from the platen. The recess lllll is centrally aligned between the pulleys 44 and 46.

. ber 82 by a spring 110. The force of the spring lid normally urges the toothed roller 162 into contact with the belts 42 as they pass over the pulley arrangements 44 and 46 to produce a tensioning of the belts The arm res is'positio-ned out of contact with an eccentric shaft Belts 42.

112. The eccentric shaft 112 extends through the frame member 63. When it is desired to release the tensioning force normally applied by the tensioning arrangement 98, the eccentric shaft 112 is turned. in response to a turning of the eccentric shaft 112, the arm we is caused to rotate at a counterclockwise direction around the pivot arrangement 1% to compress the spring Mill and force the, toothed roller 1G2 out of contact with the flexible In this position, thefiexible belts 42 may be removed from the toothed pulley arrangements i l and '46 for replacement, repair or cleaning.

'Theactuator support member do also includes a pair of inwardly flanged end portions 114 and 116 Which extendtoward the platenltl to contact the coupling members 33 and 92?, respectively. fThe coupling members 88 tween the coupling members 53 and as parallel to a plane in FEGURE l, the drive shaft 52 lies to one side, of the of the belts 42 asitliey pass the platen ll As illustrated YinFIGURE l, the hammer supporting member as is di- ,vided into two L-shaped sections lZZ'and 24.

The vl..-s i1apcd section 122 is bolted to the coupling member 83 as represented at 325, While the L-shaped member lZ d is bolted to the couplingmember m as represented base portion 13 1 ":base portion 1320f the member 12d are spaced from and divided into four-sectio'riss i, 36,88 and 9th. The support: I

.jmemberfilproyidesmeans' for supporting aj-pluralityofl hammers 2 21 first andsecondplurality ot electromag' nets Q4 and-lfi'for actuating the hammers, and an appaextend substantially parallel to each other to define a "slot 13 :3. The slot 134 is aligned with the opening 46 in the ribbon guide 38. I v 7 As represented in FIGURE 3, the base 1353 c Oi LDC L-shaped member 122 includes a. plurality of spaced grooves 136. In a similar manner, the base 132 of the L shaped member lz l includes a plurality of grooves 138.

' Each-groove l36is in aligned association with a did'erent groove 138." Pressure fitted into each pair of associated grooves 136 and 13% is a plate member 1%. The plate member 84 facing the platen lit in acornmon plane with the opening Each belt is ali ned with a different opening 42. The openings 142 are, in turn, dimensioned to the idth and spacing idhebelts 52 as the pulley arrangements 34 and as.

I [As represented in FIGURE 3, mounted for sliding-mopass over of, L-shaped member 122 and a tion within each of the openings 142 is an elongated,lightweight print hammer 92. Due to the alignment of the openings 142 with the belts 42, a print hammer 92 is aligned substantially normal to each belt 42 as well as the platen in a plane of the opening 40. The lightweight print hammers 92 each have a ramped forward face 143 facing a belt 42 and a rear face 144 extending beyond the slot 134 internal to the belt 42. As represented in FlGURE 1, the hammer92 includes a slot 146 in one'of its longitudinal surfaces. Extending into the slot 145 through an opening 148 in the base portion 131? of'the L-shaped member 122 is a spring arm The spring arm 150 forms one finger of aspring plate 151 (see FIG- URE 3) which is coupled to the member 34- as indicated at 152. The spring arm 151i is shaped to exert a force on the hammer which normally urges the hammer out of contact with its associated belt 42. p

In a similar manner, such as represented by a spring arm 154 (which forms one finger of a spring plate 155 see FIGURE 3) extending into a slot 155 of a hammer immediately adjacent the hammer 92 illustrated in FIG- URE 1, each of the hammers 232 are slidably mounted normal to the platen 10 in an opening it} and are normally urged out of contact with the belts 42.

Since the hammers 92 are normally urged away from the belts 42, to print with the print mechanism of the present invention it is necessary to propel the hammers 92 forward against the belts 42. To provide means for selectively actuating the hammers 92, the first and second plurality of electromagnets, represented generally at 94 and 96, are coupled to the actuator support member as.

The first and second plurality of electromagnets are coupled in two separate rows along a rear face or" the actuator support member 86 on opposite sides of the plurality of hammers 92. To provide for a highly compact actuator design, the armatures of the first plurality of electro magnets are interlaced with the armatures of the second plurality of electromagnets adjacent the rear face of the hammers 92. Accordingly, the armatures associated with the first plurality of electromagnets contact the rear face of alternate print hammers such as the first, third, fifth, etc. while the armatures associated with the second plurality of electromagnets 96 contact alternate print hammers such as the second, fourth and sixth, etc. The compact actuator design is further aided by alternating the location of the field structures of the first and second plurality of electromagnets relative to the actuator support member 86. Thus, as illustrated in FIGURE 1, an electromagnet 158 of the first plurality of electrcmagnets SM includes a nonmagnetic base member 168 coupled to the cludes a slot 170 into which is tightly inserted a tongue member 172. The tongue member 172 is positioned into a slot 174 which extends into a solid magnetic port on 176 of an armature 178. The armature 1'78, in addition to the solid portion 176, which extends adjacent the coil 165, also includes an arm member 1853 attached to the portion 176 as indicated and extending upward adjacent the hammers 92.

Attached to the upper end of the arm member 188 is a second solid member 182. The second solidmember 182 is positioned to strike a rear face 144 of the harnmers 92 when the electromagnet 158 is actuated;

A spring member 184 is 'coupled by pins 186 and 188 between the member 176 and the leg 169. The Spring normally urges the armature 178 to pivot around a point defined by the tongue 172 and the slot 1'74, thereby main- ,taining the member 176 away from the coil 16S andthe member 182 against a stop portion 1% of the actuator support member 86. A

A second-electromagnet 192, adjacent the electromagnet 158, also includes a nonmagnetic base member 194 coupled to the actuator support member 86 by a'screw 196. Coupled to the base member 194 is a magnetic U- shaped field structure which supports a coil 198 and an armature 200. The arrangement of the electromagnet 192 is more clearly illustrated with reference to an electromagnet 202 of the second plurality of electromagnets 96.

The electromagnet 202 and the electromagnet 192 are of similar construction except that the electromagnet 202 is inverted to extend an armature 204 downward to interlace with the armature 176 of the electromagnet 158 and the armature 2% of the electromagnet 88.

The electromagnet 202 includes a nonmagnetic base member 2116 which is coupled to the actuator support member 86 by a screw 208.. Coupled to the base 206 is a magnetic U-shaped field structure 210 for supporting a coil 212 on one of its upwardly extending legs 21 2.

As illustrated, a leg 215 of the field structure 2113 includes a'slot 216 into which is tightly positioned a tongue member 213. The tongue member 218 fits into a slot 221} in a solid magnetic member 222 of the armature 2%. The

armature 2134, in addition to the member 222, which extends adjacent the coil 212, also includes an arm member 224 which is attached to the member 222 as indicated. The arm member 222 extendsdownward adjacent the hammers 92. A second solid member 22a is attached to the arm 224 and ispositioned to strike a rear face 144 of a'hammer 92'when the electromagnet 2192 is actuated.

A spring member 228 is coupled by pins 231i and 232 between the leg 215 and the solid member 222, The spring 228 normally urges the armature 2134 to pivot around a point defined by the tongue 218 and the slot 220 to maintain the member 222 away from the coil 212 and the member 226 against the stop portion 191? of the actuator support member 86.

An electromagnet 234, adjacent the electromagnet 2112,

is coupled to the actuator support member 86 by a screw 236 extending into its base member 238. The electromagnet-234= is constructed similar to the electromagnet 15% previously described. Thus, the coilsof the electromagnets of the first and second plurality of electromagnets are alternately located adjacent to and remote from the actuator support member 86 internal to the belts 42. This provides a highly compactspacing ofthe armatures of electromagnets of the first and second plurality of electromagnets and thus, together with the aforementioned interlacing of armatures, allows a maximum number of electromagnets to be mounted in a minimum of space.

As illustrated in FIGURE 3, the support member 82 is coupled directly to a frame member 241 by a pair of screw members 241 and 242. The frame member 240 extends substantially normal to the platen 19. "in this manner the support'member 82, including the hammers 92, the plurality of electromagnets 24 and as as well as the belt tension apparatus 98, is cantilevered from the frame 240 to extend internal to the belts 42. To provide additional support for the support member 82, the supcantilevers from the frame .member 63 and is supported in the bore 253 by the frame member 2211. In a similar manner the driven shaft 63 is cantilevered from the frame member $12 and is supported in the bore 252of the frame forced toward the platen.

.plastic provides superior print characteristics.

1? v member 240. This construction provides for a simple sliding assembly of the printer as well as case in replacing any part of the print mechanism for maintenance purposes. 7

To print with the present invention the electromagnets re selectively energized to strike the rear face of particular print hammers. To actuate the first and second plurality of electromagnets, a plurality of electrical conduct'ors, indicated by the wire tubes 254 and 255, extend from outside the printer through the frame member 24%).

A pair of wires from the wire tube 254 is coupled to each coil of the first plurality of electromagnets 94 while a pair of wires from the wire tube 255 is coupled to each 'coil of the second plurality of electromagnets 96. Thus,

by selectively energizing particular pairs of wires, particular electromagnets may be energized.

In response to a momentary current flow through a particular coil, the armature associated therewith is attracted toward the coil to cause the arm of the armature to strike the rear face of its associated print hammer.

The hammer is propelled towardthe belt associated therewith.

characters disposed on the flexible belts.

In practice, extremely clear printing of the type characters is produced with the print mecharisrn of the present invention. This is due in part to the flexibility of the belts 42 as well as the rapidity of the hammer operation. When a hammer strikes a tooth of one of the belts the belt stretches slightly as the type character is While the type character is pressing against the platen, the belt associated therewith continues to move. However, due to the flexibility of the belt, the belt stretches slightly to allow the type char- When the hammer its normal position ready for another print operation.

' Such flexibility may be provided by belts of different composition. For example, the belts may be of metal, rubber, plastic or other materials of high strength and long flex life. Although any of the above materials may be utilized, it has been found that a belt composed of Such a belt may be formed in a single mode operation and possesses the characteristic that it becomes stronger as it a print actuating mechanism mounted internal to the flexible belts, provides a compact, rapid acting printer for printing on documents of varying sizes at extremely high speeds.

What is claimed is:

1. A high speed printer comprising:

a platen;

a plurality of continuous, flexible belts, each belt having plurality of lightweight elongated hammers aligned in a common plane and mounted for sliding movement on the support member substantially normal to the platen, each hammer having a forward face aligned with and immediately adjacent to a different belt;

a first plurality of electromagnets coupled to the sup port member on one side of the plane of the hammers, the electromagnet of the first plurality of electromagnets each having an armature, the armaturesiof the first plurality of electromagnets being hinged to strike a rear face of alternate ones of the hammers to propel the alternate hammers against alternate belts toward the platen;

a second plurality of electromagnets coupled to the support member on an opposite side of the plane of the hammers, the electromagnets of the second plurality of electromagnets each having an armature, the armature of the second plurality of electromagnets being interlaced with the armatures of the first plurality of electromagnets and hinged to strike a rear face of alternate hammers to propel the alternate hammers against alternate belts toward the platen.

2. A high speed printer comprising:

a platen;

a first frame member;

a drive shaft journalled to the first frame member to V extend substantially parallel to the platen;

a driven shaft journalled to the first frame member to extend substantially parallel to the platen member in a common plane with the drive shaft;

a plurality of continuous flexible belts, each belt having type characters disposed on its outer surface, each belt also being directed in driving engagement over the drive shaft and driven shaft, respectively;

a second frame member;

a support member coupled to the second frame member internal to the belts;

a plurality of print hammers coupled to the support member for movement substantially normal to the platen, each hammer being aligned with and adjacent to a diiferent belt;

and means coupled to the support member for selectively propelling each print hammer against a belt to force a type character against the platen.

3. The apparatus defined in claim 2 wherein the print hammers are lightweight elongated hammers slidably mounted on the support member for movement normal to electromagnets coupled to the support member, each electromagnet having an armature hinged to strike a different elongated hammer when the electromagnet is energized, the apparatus also including means for normally urging each hammer away from the platen and out of contact .with the belts.

4. The apparatus defined in claim 2 including means coupled to the support member and impinging the belts for tensioning the flexible belts to maintain the belts over the drive and driven. shafts.

5. The apparatus defined in claim 4 including means for disengaging the means for tensioning to allow the belts to be removed from the drive and driven shafts.

6. A high speed printer, comprising: a platen; means for clamping aprint medium to the platen; a plurality of continuous belts each forming a closed loop and each carrying an array of type characters on a surface facing the platen;

means for movably supporting the belts in closely spaced relationship such that type characters on adjacent belts are spaced apart only slightly more than the width of the belts,

means for moving the belts to transport the type characters in succession adjacent the platen such that each one of the plurality of type characters carried by each of the belts is successively positioned directly 9 l9 opposite a different predetermined area of the print a plurality of continuous belts, each belt forming a medium clamped to the platen; closed loop and each having a plurality of type charand a plurality of print units positioned within the loop acters disposed on its outer surface;

of the belts, each print unit being associated with a means for aligning the belts side by side to pass over the dilTerent belt and including means for striking a surdrive shaft and the driven shaft such that each belt face of its associated belt remote from the platen to is aligned with a different character space on the print press a selected one of the type characters on the belt medium and that rotation of the drive shaft causes into engagement with the print medium when the each one of the plurality of type characters to be selected character is opposite the associated predesuccessively positioned directly opposite the charactermined area on the print medium. 10 ter spaces with which the belts are aligned;

7. In a high speed printer for printing a plurality of a plurality of print units positioned between the drive characters on a print medium passing closely over a and driven shafts and mounted within the loop of platen, the combination of: the continuous belts, each print unit being associated a plurality of continuous belts each forming a closed with a different belt and each including means for loop and each carrying an array of type characters striking a surface'of an associated belt remote from on a surface facing the platen; the platen to press any selected one of the type charmeans for movably suppor ing the be s in closely acters against the print medium in the associated spaced relationship such that type characters on adcharacter space when the selected type character is jacent belts are spaced apart only slightly more than opposite the associated character space. the width of the belts; 10. The apparatus defined in claim 9 wherein each print means for moving the belts to transport the type charunit includes a lightweight print element aligned with a acters in succession adjacent different areas of the belt to strike an inner surface of the belt remote from the print medium clamped to the platen; platen and an electromagnet having an armature hinged a plurality f print el ments positioned Within th loop to strike a side of the print element remote from the platen of the belts, each Print element being HSSOCiated With to propel the print element against the associated belt a ditferent belt and being mounted to strike a face of when the electromagnet is excited.

the associated belt remote from the platen to press a type character against the print medium; References Cited in the file of this patent and means positioned within the loop of the belts for D ATES PATENT propelling selected print elements against their asso- UNITE ST S ciated belts to produce a selected printing of a plu- 2,053,063 Bryce P 1, 1936 rality of type characters on the print medium. 210931545 Y et a1 p 1937 8. The apparatus defined in claim 7 including means 1 L M1165 1937 for normally urging each print element away from th 7 3 Crawford 1956 platen, 2,831,424 MacDonald Apr. 22, 1958 9. In a high speed printer for printing a plurality of 2,918,865 Wooding Dec. 29, 1959 characters in a plurality of aligned character spaces on a 2,950,048 Luhn Aug. 23, 1960 print medium passing over a platen, the combination of: 2,990,767 Demer et al- July 4, 1961 a drive shaft; 3,012,499 Amada Dec. 12, 1961 a driven shaft; 40 3,041,964 Simpson July 3, 1962 

1. A HIGH SPEED PRINTER COMPRISING: A PLATEN; A PLURALITY OF CONTINUOUS, FLEXIBLE BELTS, EACH BELT HAVING TYPE CHARACTERS DISPOSED ON ITS OUTER SURFACE; MEAN FOR MOVING EAFH BELT TO PASS TYPE CHARACTERS IN SUCCESSION ADJACENT TO THE PLATEN; A SUPPORT MEMBER MOUNTED INTERNAL TO THE BELTS; A PLURALITY OF LIGHTWEIGHT ELONGATED HAMMERS ALIGNED IN A COMMON PLANE AND MOUNTED FOR SLIDING MOVEMENT ON THE SUPPORT MEMBER SUBSTANTIALLY NORMAL TO THE PLATEN, EACH HAMMER HAVING A FORWARD FACE ALIGNED WITH AND IMMEDIATELY ADJACENT TO A DIFFERENT BELT; A FIRST PLURALITY OF ELECTROMAGNETS COUPLED TO THE SUPPORT MEMBER ON ONE SIDE OF THE PLANE OF THE HAMMERS, THE ELECTROMAGNET OF THE FIRST PLURALITY OF ELECTROMAGNETS EACH HAVING AN ARMATURE, THE ARMATURES OF THE FIRST PLURALITY OF ELECTROMAGNETS BEING HINGED TO STRIKE A REAR FACE OF ALTERNATE ONES OF THE HAMMERS TO PROPEL THE ALTERNATE HAMMERS AGAINST ALTERNATE BELTS TOWARD THE PLATEN; A SECOND PLURALITY OF ELECTROMAGNETS COUPLED TO THE SUPPORT MEMBER ON AN OPPOSITE SIDE OF THE PLANE OF THE HAMMERS, THE ELECTROMAGNETS OF THE SECOND PLURALITY OF ELECTROMAGNETS EACH HAVING AN ARMATURE, THE ARMATURE OF THE SECOND PLURALITY OF ELECTROMAGNETS BEING INTERLACED WITH THE ARMATURES OF THE FIRST PLURALITY OF ELECTROMAGNETS AND HINGED TO STRIKE A REAR FACE OF ALTERNATE HAMMERS TO PROPEL THE ALTERNATE HAMMERS AGAINST ALTERNATE BELTS TOWARD THE PLATEN. 